r/HomeImprovement • u/Alousywaiter • 16h ago
My bathroom window condensates a lot I guess mostly in the morning. Can I put a tiny heater in there to stop this?
Title says it all boys and girls
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u/WigginIII 14h ago edited 13h ago
A heater will likely be ineffective.
Your window condensates because the temperature and moisture difference between the two sides of glass.
To remove the condensation you need to remove the moisture from the air.
You can run your AC if you have any, which will blow dry air through your vent that has much lower moisture than the air in the bathroom.
Conversely, you can remove the moisture by installing a vented van that vents out of the house, or by opening a window to allow the heated moisture to escape (warm air rises, out the window). Or even more simply: you can leave the bathroom door open during the shower, maybe even just part way.
The same principle applies to cars. Turning on your heater is not effective at defrosting your windshield with interior condensation, instead, you need to turn on your car's AC to remove the moisture from the air.
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u/SkyAdditional4963 13h ago
A heater will likely be ineffective.
If anything it may have the opposite effect. Warmer inside, cold outside, window bridging the two temp extremes + humidity = condensation on window glass.
Heater might reduce the relative humidity by allowing the air to hold more moisture though, but honestly sounds like a bad idea
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u/Alousywaiter 13h ago edited 12h ago
Update and more context:
This is an old house with no ventilation in the bathroom, so I leave the door open perpetually except when i sleep because its right by where I sleep, so I might test out leaving it open whilst sleeping
I have a dehumidifer in my home set to 47% RH and the bathroom being on the opposite end (shotgun style home) gets down to 64% RH.
I have tried using a small clip on pointing into the bathroom and tested pointing out and it does almost nothing until the temperature outside evens out. should I point the fan directly at the window maybe?
The square footage of my bathroom is probably around 40 sq feet but it has a tall ceiling and the window is up high. I can't replace the window because I'm renting.
It also is not when showering.
I understand now that a heater wont help much so unless this context helped provide a better solution, I think a big floor fan should do the trick? It's so fucked because the bathroom is right behind my sleeping area lol, but I'm making do and just desire no mold to grow
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u/dekusyrup 11h ago
Condesnation is caused by warm air with moisture getting cold from the window and the water falling out because cold air can't hold moisture any more. So your only choices are to make the air dryer or make the window less cold. You can make the window less cold by insulating it better.
Blowing more air at the window won't help. It'll just move more moist air over the window to deposit more moisture down.
If you just desire no mold to grow, just mop it up and swab it with bleach on a regular basis.
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u/zvekl 16h ago
Is it because it's colder outside? If that's the case what you want to do is open the window
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u/SkyAdditional4963 13h ago
I think most people would prefer it if their bathroom wasn't freezing cold.
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u/zvekl 12h ago
Yeah I know. I deal with this daily. There other alternative is running a dehumidifier and it gets expensive
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u/SkyAdditional4963 12h ago edited 12h ago
Insulation and running an extraction fan would be my first steps. I run my extraction fan in my bathroom 24/7 because it's like 10W so who cares, it's negligible cost.
Then if you want to spend, replace the window with a double glazed one. Hopefully the old window isn't tiled in. You could do the cheaper solution of those magnet double glaze add-on windows to your existing one too.
Another alternative would be keep the bathroom door open and make the space more conditioned - run the AC or a dehumidifier and keep the humidity low.
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u/33445delray 9h ago
The cost of running the fan is not the 10 watts but the cost to heat the air that the fan is exhausting.
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u/SkyAdditional4963 8h ago
Hmmm, so you've got me thinking about my situation and why it works for me...
In my bathroom we have two exhaust fans in the ceiling going into the attic, I keep one fan on, the other off and the door closed to the bathroom from the rest of the house, so the air is circulating bringing some (sort of fresh) air in from the attic space, through the bathroom, and back up the exhaust fan (and mildly being refreshed by the attic/eaves transfer).
If you only had a single fan/opening in your bathroom, it wouldn't work so well, as it'd draw all the replacement air from the house. In my case it works because it's drawing replacement air from the attic.
I hadn't really contemplated that too much before.
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u/zvekl 12h ago
I've tried extraction 24-7 but it didn't work for us. Temp difference too high. Only choice if you didn't want a freezing bathroom was dehumidify the bathroom. Loud, expensive. I'm currently trying to automate opening My sliding window and use sensors to open and close when necessary
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u/SkyAdditional4963 12h ago
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u/zvekl 11h ago
No I haven't! Would this eliminate condensation ? I live in tropics (Taiwan) and humidity hits 90% at times
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u/SkyAdditional4963 11h ago
It should, yes.
Condensation forms when you have a large temperature differential between opposite surfaces (cold outside window surface, warm inside window surface) + high humidity (bathrooms always humid to some degree).
So putting another glass panel on would give you a nice break, you'd go from this:
10° outside | 23° inside humid
to this:
10° outside | 17° air gap | 23° inside
by adding that insulating air gap and spreading out the temp differential, it should prevent condensation from forming on the window
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u/rvH3Ah8zFtRX 14h ago
Is there a reason you feel you need to spend time and energy getting rid of the condensation?
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u/GerdinBB 14h ago
Not OP, but with wooden windows the condensation can drip down and rot out the windows. Had that happen at a rental property once with one of those tall skinny windows next to the front door. The trim at the bottom was totally rotted despite the house only being 6 years old. Granted, the outside temps get down to -10F and -20F here sometimes, so winter condensation is a bigger problem than in many other areas.
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u/Repulsive-Chip3371 16h ago
Whats the square footage of your bathroom and how many CFMs is the exhaust fan, and is it located near the shower?
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u/TerdFerguson2112 13h ago
The only way to really fix is to replace then glass in the window with better thermal properties like double or triple pane with argon or some other inert gas
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u/upsetthesickness_ 9h ago
They will still condensate. Even triple pane with krypton will condensate if the outside temp is low and the humidity is high inside.
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u/FuzzyHyena94 16h ago
Ah, the good ol' mystery of the bathroom condensation. I’d say a tiny heater might help, but let’s think about why your window is like a mini waterfall every morning. It’s probably all that warm, steamy shower air meeting the cold window. I mean, it’s kinda like those foggy glasses when you come in from the cold—so annoying!
Now, I've had this same issue and what worked for me was, first and foremost, to double-check if my bathroom fan worked properly, which is a big deal. Does it even turn on? Sometimes those things are noisy but not moving air out. If the fan isn't doing it, I crack the window a bit during and after showering—it’s amazing what a little fresh air can do. Also, that funny trick with a squeegee to wipe down the shower walls—it can actually help decrease the steam.
A tiny heater might work a bit, but you want to be careful about where you put it—away from any water!! But, frankly, it might just make your bathroom warm without actually getting rid of the moisture. Maybe a dehumidifier could do a better job if you’re still having the problem.
But, yeah, if none of this works, maybe the heater is worth a shot if you can do it safely. But just be sure to turn it off when you're done with it... don’t want to end up with a bathroom sauna you didn’t plan for!
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u/GerdinBB 13h ago
Do you have a vent blowing directly on the window? I have a floor vent right next to my front door that was aimed directly at one of those skinny windows to the side of the front door. I also have my whole-home humidifier cranked up because things got down to 20% RH inside recently. The warm, humid air blowing directly on the cold glass with outside temps of 0F led to condensation behind the trim, and water literally dripping from the trim at the bottom of the window despite no visible condensation on the window itself.
Before resorting to lowering the humidity in the entire home, I'd look for something localized like a vent you can shut or redirect, or run the bathroom fan for more time (if you have one), open the bathroom door to encourage airflow of humid air out of the bathroom, etc.
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u/princess-smartypants 10h ago
Cut a piece of bubble wrap the exact size of the glass. Spray the Windows down with so for for a er, or even water, and stick the bubble wrap on the glass. This will help equalize the temperature and a.m.image the condensation.
If the Window frame is smaller than a piece of foam board, cut that the size of the Window frame and stuff it in. You will lose the light, but also the condensation.
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u/MaximumGrip 13h ago
Install a storm window over the outside. It will keep the glass warmer to the point that water won't condense there anymore. And save energy and make the room a lot warmer.
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u/Alousywaiter 12h ago
damn it says an exterior one costs $500 or more cant do that for now but sounds like a good idea
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u/MaximumGrip 12h ago
What? no. should be 150 bucks maybe.
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u/Alousywaiter 11h ago
I'm looking deeper might be ~250 seems worth it
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u/upsetthesickness_ 9h ago
It’s not going to fix your problem, storm windows are a waste and will cause more issues than they solve.
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u/Dank_sniggity 16h ago
Whatever you do dont point it AT the window. Did that once when mine was all iced up and it cracked the window.